Really? I never heard any sound, while the underbody touches the ground or a high curb. Maybe a matter of sound setting. There seems to be also no decrease of speed, even when the car scrubs over the tarmac, at almost the whole length of the straight. I tested with very soft springs, lowest packers and high downforce. Static rideheight was about 30 front/65 back. Dynamic rideheight was around zero (checked with Motec), most part of the straight.